1. Field of the Invention
The present invention relates to a cardiac monitor and, specifically to methods and apparatus using detectors and measurements provided thereby of cardiac functions for determining ventricular pressure-size curves, pre-ejection potentials, post-ejection potentials, cardiac efficiency, cardiac metabolic rate, cardiac power, pre-ejection power, and contractility for comparison with preestablished levels to allow diagnosis and monitoring of myocardial impairment, dysfunction, sufficiency, and insufficiency of an individual.
2. Description of the Prior Art
Presently, hemodynamics measures a multiplicity of parameters and compares them against an empirically established norm. As disclosed in 1978 by Yang, et al. in a work entitled From Cardiac Catheterization Data to Hemodynamic Parameters, published by F. A. Davis Co., Philadelphia, Pa. 1978, a heart rate of between 60 and 100 beats per minute and a blood pressure of 120/80 mm Hg are considered normal. Also, a cardiac output, CO, of 5 l/min is considered to be normal. Yet, CO may have a normal numeral value computed according to CO=SV * HR as, for example, may be the result of an abnormal stroke volume, SV, of 42 ml which is compensated by an abnormally high heart rate, HR, of 120 l/sec. Furthermore, a stroke volume of 70 ml, considered to be normal, may be caused by an abnormal end-diastolic volume, EDV, of 270 ml and an abnormal end-systolic volume, ESV, of 200 ml, when computed according to SV=EDV-ESV. Therapies are subjectively developed based on physicians' experience to correct one or more hemodynamic outliers to return to the normal range.
In contrast to hemodynamics, the present invention utilizes actual measurements of cardiac functions for diagnosing efficiency and cardiac power to assess the performance of the heart as a working system and objectively develop therapies to cause the heart to work efficiently and sufficiently based on ventricular pressure-size curves.
It is therefore an object of the present invention to diagnose a cardiac condition of a subject by obtaining select measurements of cardiac functions for determining the present ventricular pressure-size curves and the present working efficiency represented thereby of the heart as a pump in the circulatory system and comparing such present ventricular pressure-size curves and present working efficiency with pre-determined reference pressure-size curves and working efficiency representing a normal subject at rest.
It is another object of the present invention to determine present pre-ejection potential using cardiac measurements of cardiac functions, pre-ejection potentials and post-ejection potentials indicative of the manner in which a subject performs cardiac work and comparing the subject's pre-ejection potentials and post-ejection potentials with pre-determined reference pre-ejection and post-ejection potentials of a normal with deviations thereof being an indicator of improper cardiac functions.
It is still another object of the present invention to determine present sufficiency of the heart using measurements of cardiac functions in terms of cardiac power and compare the present cardiac power of the subject with the threshold cardiac power needed to sustain life where a deficiency of cardiac power expended indicates an insufficiency or a life-threatening emergency and an excess of cardiac power expended indicates the existence of a dysfunction of the organism.
It is further an object of the present invention to determine whether the dysfunction, represented by an excess of cardiac power requirement is compensated sufficiently, as indicated by high magnitudes of cardiac efficiency, or insufficiently, as indicated by low magnitudes of cardiac efficiency in case of myocardial impairment by the use of measurements of cardiac functions.
It is still another object of the present invention to determine maximum pre-ejection power the heart must attain and the fraction thereof which the heart must expend to sustain life and overcome a dysfunction.
It is furthermore an object of the present invention to provide a method and apparatus to practice cardiac efficiency and sufficiency diagnostics using measurements of cardiac functions to identify and to monitor therapies which permit the heart to work efficiently and sufficiently.